Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Millions		Jan. 31, 2016	Jan. 25, 2015
Financial assets and liabilities measured at fair value
Interest Rate Swap, at Fair Value	[1]	$ (7)	$ 0
Corporate Debt Securities
Financial assets and liabilities measured at fair value
Cash and Cash Equivalents, Fair Value Disclosure		51	147
Marketable Securities		1,850	2,040
US Government Agencies Debt Securities
Financial assets and liabilities measured at fair value
Cash and Cash Equivalents, Fair Value Disclosure		90	15
Marketable Securities		1,080	735
Fair Value, Inputs, Level 1 | Money Market Funds
Financial assets and liabilities measured at fair value
Estimated Fair Value	[2]	43	132
Fair Value, Inputs, Level 2
Financial assets and liabilities measured at fair value
Convertible Debt, Fair Value Disclosures	[3]	2,273	1,680
Interest Rate Swap, at Fair Value	[1]	(7)	0
Fair Value, Inputs, Level 2 | Corporate Debt Securities
Financial assets and liabilities measured at fair value
Estimated Fair Value	[4]	1,901	2,186
Fair Value, Inputs, Level 2 | US Government Agencies Debt Securities
Financial assets and liabilities measured at fair value
Estimated Fair Value	[5]	1,170	750
Fair Value, Inputs, Level 2 | US Treasury Securities
Financial assets and liabilities measured at fair value
Estimated Fair Value	[6]	801	537
Fair Value, Inputs, Level 2 | Asset-backed Securities
Financial assets and liabilities measured at fair value
Estimated Fair Value	[7]	435	453
Fair Value, Inputs, Level 2 | Mortgage backed securities issued by United Sates government-sponsored enterprises
Financial assets and liabilities measured at fair value
Estimated Fair Value	[6]	231	278
Fair Value, Inputs, Level 2 | Foreign Government Debt Securities
Financial assets and liabilities measured at fair value
Estimated Fair Value	[6]	$ 92	$ 85

[1] Please refer to Note 9 of these Notes to the Consolidated Financial Statements for a discussion regarding our interest rate swap.

[2] In cash equivalents on the Consolidated Balance Sheets.

[3] The Notes are carried on our Consolidated Balance Sheets at their original issuance value, net of unamortized debt discount, and are not marked to fair value each period. Please refer to Note 11 of these Notes to the Consolidated Financial Statements for additional information on the Notes.

[4] Includes $51 million and $147 million in cash equivalents as of January 31, 2016 and January 25, 2015, respectively, and $1.85 billion and $2.04 billion in marketable securities as of January 31, 2016 and January 25, 2015, respectively, on the Consolidated Balance Sheets.

[5] Includes $90 million and $15 million in cash equivalents as of January 31, 2016 and January 25, 2015, respectively, and $1.08 billion and $735 million in marketable securities as of January 31, 2016 and January 25, 2015, respectively, on the Consolidated Balance Sheets.

[6] In marketable securities on the Consolidated Balance Sheets.

[7] Includes $435 million and $453 million in marketable securities as of January 31, 2016 and January 25, 2015, respectively, on the Consolidated Balance Sheets.